mm/migrate: fix shmem xarray update during migration
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.1.132, 6.6.85, 6.12.21, 6.13.9
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/migrate: fix shmem xarray update during migration A shmem folio can be either in page cache or in swap cache, but not at the same time. Namely, once it is in swap cache, folio->mapping should be NULL, and the folio is no longer in a shmem mapping. In __folio_migrate_mapping(), to determine the number of xarray entries to update, folio_test_swapbacked() is used, but that conflates shmem in page cache case and shmem in swap cache case. It leads to xarray multi-index entry corruption, since it turns a sibling entry to a normal entry during xas_store() (see [1] for a userspace reproduction). Fix it by only using folio_test_swapcache() to determine whether xarray is storing swap cache entries or not to choose the right number of xarray entries to update. [1] https://lore.kernel.org/linux-mm/Z8idPCkaJW1IChjT@casper.infradead.org/ Note: In __split_huge_page(), folio_test_anon() && folio_test_swapcache() is used to get swap_cache address space, but that ignores the shmem folio in swap cache case. It could lead to NULL pointer dereferencing when a in-swap-cache shmem folio is split at __xa_store(), since !folio_test_anon() is true and folio->mapping is NULL. But fortunately, its caller split_huge_page_to_list_to_order() bails out early with EBUSY when folio->mapping is NULL. So no need to take care of it here.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From be72d197b2281e2ee3f28017fc9be1ab17e26d16 · fixed in 49100c0b070e900f87c8fac3be9b9ef8a30fa673; From 07550b1461d4d0499165e7d6f7718cfd0e440427 · fixed in 29124ae980e2860f0eec7355949d3d3292ee81da; From fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c · fixed in c057ee03f751d6cecf7ee64f52f6545d94082aaa; From fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c · fixed in 75cfb92eb63298d717b6b0118f91ba12c4fcfeb5; From fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c · fixed in 60cf233b585cdf1f3c5e52d1225606b86acd08b0; From 6.1.71 · fixed in 6.1.132; From 6.6.10 · fixed in 6.6.85
- Linux Linux
6.7
- KernelLinux
fixed in 6.1.132; From 6.2.0 · fixed in 6.6.85; From 6.7.0 · fixed in 6.12.21; fixed in 6.13.9